Police have warned social media could fuel copycat crimes after strangers put out a fire they believe was started in the door of a Paraparaumu Beach dairy by three teens, just six days after three girls allegedly burned down a large part of Paraparaumu School.

The trio and the fire at the Manly St Superstore were spotted just before 10pm by a passing taxi driver whose passengers stamped out the fire and chased the teens.

Community constable Jacquie Muir confirmed police arrested a 16 and a 17-year old on Saturday night connected to the incident.

The pair face charges of attempted arson, and are due to appear in Porirua Youth Court on Thursday.

No further information was available from police, however Muir restated police concerns about wide social media comment surrounding the Paraparaumu School fire, this time warning the discussions could lead to more arsons.

‘‘Police urge parents, caregivers and young people to consider carefully before using social media outlets discussing arson as it often incites and encourage this type of behaviour,’’ she said.

The Raumati couple who had been travelling in the taxi and helped at the Manly St fire scene wished to remain anonymous, but both said it was surreal to see what was happening so soon after the arson at Paraparaumu School.

‘‘All of a sudden the taxi driver just slammed on his brakes and I looked out the window and there were these three boys setting fire to the dairy; they had paper in a backpack and one was stuffing it under the security grill,’’ the woman said.

‘‘One was down on his knees [at the fire], with a cap on; the flames were quite high, they were over his head.

‘‘I screamed at him as I leapt out, I said ‘‘what are you doing?’’

He just carried on doing whatever he was doing with his backpack and just calmly got up and walked away.’’

Her partner then chased the three teens to nearby Falla St, where they got away, while she began pulling burning newspaper onto the pavement and stomping the flames out.

Two other women pulled over, and poured water on the remnants of the burning paper, while the taxi driver called the fire brigade, she said.

Her partner said two older teenagers then approached and offered to help, saying they were previous Paraparaumu School pupils.

They joined the hunt for the three, finding one in a yard, before he got away. However a cell phone left behind at the scene where the teen had been kneeling at the fire was left undisturbed and was able to be pointed out to police, the man said.

Manly St Superstore owner operator Jay Gandhi said he learned of the fire the next morning when he found the charred remains in the store’s doorway, but was shocked and thankful to the people who put it out.

He also found a large stone near the front window of the building, and believed the teens had planned to throw it through the window.

‘‘I’ve been here for the last 14 years, and these things have not happened before.

‘‘The community’s all very good here, helping each other — I’m very happy that we are together; it was shocking what could have happened next if that taxi driver had not seen it,’’ he said